[swift-evolution] [proposal] Either in the Swift Standard Library

[Developer]

Because the last discussion, while substantive and very much appreciated, did not debate the proposal much, I'd like to begin discussion anew about the addition of an Either type to the Swift Standard Library.  The proposal can be found here (https://github.com/apple/swift-evolution/pull/67#issuecomment-170269481) and a link to the root our previous round of discussion is here (https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001394.html).

Thanks all!

~Robert Widmann